A great number of devices with which drinking water is mixed with gas, such as, for example, CO2 or O2, is known. Most of these devices include a specially designed mixing means taking care of a fine distribution of the gas in the water which cannot be achieved by simple joining, possibly under elevated pressure. Such a mixing means is known, for example, from DE 10055856. The known mixing means includes a microstructure which finely distributes the water as well as the gas and combines them subsequently, so that the absorption of carbon dioxide is highly increased by the increased surface area of the water.
Another mixing means is known from WO 2006/012874 where it has been found out that the circulation pumps or booster pumps often used in dispensing equipment can also be used for carbonizing if they are combined with a reduction of the cross-sectional area in the applied line, providing further increase of pressure.
It is finally known from WO 2005/009598 to employ a turbulence means for mixing water with gas. The known means is preferably designed for introducing oxygen into salt water for supplying aqua-farms for marine animals. However, it can also be employed for carbonizing. In this citation, the centrifugal force is utilized by tangentially introducing a gas-water mixture into a cylindrical housing to improve the mixing result.
The known solutions, however, are normally quite complex and expensive. With the passive solutions (microstructure), the result moreover highly depends on the water's primary pressure which can possibly vary. The pump solution is substantially independent of the water's primary pressure, but it is only profitable where a correspondingly efficient pump has to be provided anyway.